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Biomedical subjects

G Ross

Publications and source records attributed to G Ross.

At least 217 records · Page 12Linked to original sources
PubMed1980

Spontaneous phasic activity of isolated human coronary arteries.

The functional behaviour and pharmacological responses of ring segments of large coronary arteries removed from five patients undergoing cardiac transplantation were studied in vitro. All segments showed spontaneous rhythmic contractions which were markedly dependent on external calcium and were rapidly abolished in calcium-free solutions and by verapamil. The contractions were inhibited by cooling and by anoxia. Phasic activity was enhanced by increasing the external potassium concentration over the range 5 to 20 mmol.litre-1 but was abolished by 120 mmol.litre-1 potassium. Noradrenaline and ergonovine enhanced or induced phasic activity. The behaviour of human coronary arteries resembles that of the portal-mesenteric veins of many species and our results suggest that the activation mechanisms of these two tissues may be similar.

Adult↗
PubMed1980

The effect of chemotherapeutic agents on the ultrastructure of transitional cell carcinoma in tissue culture.

Human transitional cell carcinoma was successfully grown in short-term tissue culture in 17 of 29 specimens collected (58 per cent). Morphologic parameters of the explants were studied with light and transmission electron microscopy before and after incubation with either thiotepa or 5-fluorouracil. Thiotepa was found to produce marked acantholysis in 43 per cent of those studied. We postulate that thiotepa acts primarily through breakdown of cell adherence. Changes found with 5-fluorouracil were primarily confined to the nucleus.

Antineoplastic Agents↗
PubMed1980

Combined I125 seed implant and external irradiation for carcinoma of prostate.

Localized carcinoma of the prostate was treated in 20 patients by pelvic lymph node dissection, radioactive iodine implant and external radiotherapy. Treatment was well tolerated. Pelvic lymph node involvement was present in 35% of the patients. Well-differentiated cancers were essentially in small prostates (3 cm), stages T1 or T2. They had a lower possibility (10%) of metastasis to only one pelvic lymph node. None had more than one lymph node involved. Moderately or poorly-differentiated cancers occurred in larger prostates (4 cm or more), stage T3. They had a high likelihood (60%) of pelvic node involvement.

Aged↗
PubMed1979

Plasma and urine cyclic nucleotide levels in malignant disease and cirrhosis of the liver.

Plasma and 24-hour urinary cyclic AMP and cyclic GMP levels were determined by saturation analysis in specimens from normal subjects and from 101 patients with tumours of the gastrointestinal tract, breast, lung, bladder or prostate, or with cirrhosis of the liver. Relative to 46 control subjects, plasma cyclic GMP concentrations were significantly elevated in seven patients with gastric tumours, 20 patients with cancer of the breast, six patients with lung cancer, and 12 patients with cirrhosis of the liver. Urinary cyclic GMP/creatinine ratios were significantly increased in cirrhotic patients and in the lung and oesophageal cancer groups. In no cancer group were increases in plasma or urine cyclic GMP levels sufficiently consistent to be of value in the diagnosis of human malignant disease. Changes in extracellular fluid cyclic nucleotide levels in the cirrhotic group were very similar to those that have been reported for primary hepatoma patients.

Adult↗
PubMed1979

Relative biological effectiveness of low- and high-LET radiotherapy beams for jejunal crypt cell survival at low doses per fraction.

In order to determine the relative biological effectiveness (RBE) of various low- and high-LET radiotherapy beams of low coses, LAF1 mice were exposed to one dose and 10 equally fractionated doses of 60Co gamma rays, 137Cs gamma rays, 4-MeV x rays, 300-kVp x rays, helium ions in the plateau and Bragg-peak region, and 15-MeV neutrons; survival of jejunal crypt cells with the microcolony assay of Withers and Elkind was determined using 60Co as the standard. RBE values for the survival of 10 cells/circumference for 10 fractionated exposures (2.4 Gy [240 rad] per fraction of 60Co) were: 1.07 for 137Cs, 1.06 for 4-MeV x rays, 1.16 for 300-kVp x rays, 1.10 for helium ions in the plateau, 1.29 for helium ions in the peak, and 3.02 for 15-MeV neutrons. As LET increased, RBE increased with decrease of dose/fraction.

Animals↗
PubMed1979

Time course of serotonin-induced vasoconstriction.

Canine cerebral arterial segments tested in a tissue bath were found to escape from the vasoconstrictor effects of serotonin, the basilar segments more rapidly than the middle cerebral segments. At low doses (10(-9) M), serotonin caused a small, prolonged contraction, whereas at higher doses (10(-6) M), a more forceful phasic response was seen. Verapamil blocked the phasic portion of the response but not the low amplitude sustained portion. Increasing the bath concentration of K+, Ba++, and tetraethylammonium markedly enhanced the constrictor response of low serotonin doses and significantly inhibited escape. Potentiation of the force and duration of vasoactive amine-induced arterial constriction by small increments of extracellular K+ might be important in the prolonged vascular narrowing associated with subarachnoid hemorrhage.

Animals↗
PubMed1978

Permanent cutaneous ureterostomy: 18 years of experience.

We have reviewed 84 patients managed with cutaneous ureterostomy during the last 18 years. If at least 1 hypertrophied and dilated ureter is available cutaneous ureterostomy is a safe and effective diversion, with satisfactory late functional results. Stomal stenosis remains a continuing problem but usually is managed easily if present. Cutaneous ureterostomy should be used in selected patients until the ideal form of vesical substitution is achieved.

Adolescent↗
PubMed1978

Experience with the radioimmunoassay for parathyroid hormone in the diagnosis of primary hyperparathyroidism.

Our results with radioimmunoassay studies for parathyroid hormone performed during the last 6 years are compared retrospectively to results of the laboratory tests customarily secured when hyperparathyroidism is suspected. The results obtained in patients with known primary hyperparathyroidism and in patients with unconfirmed but presumptive hyperparathyroidism are compared to the results obtained from a group of normal controls. Despite the fact that certain discrepant results were noted in the earlier assay techniques the over-all results and, in particular, those of more recent years have been highly sensitive and reproducible corroboratives of the existence of primary hyperparathyroidism. About two-thirds of the patients with primary hyperparathyroidism will present to the urologist. All patients with calcium-containing stones should have at least 3 determinations of the serum calcium in screening for primary hyperparathyroidism. The radioimmunoassay for parathyroid hormone provides the most reliable confirmation. The patient with calculous disease, elevation of the immunoreactive parathyroid hormone level and hypercalcemia is virtually certain to have primary hyperparathyroidism.

Animals↗
PubMed1978

Effects of endogenous prostaglandin E on intestinal motility.

The role of endogenous prostaglandin E (PGE) in the regulation of intestinal motility in situ was studied in cats anesthetized with pentobarbital. The basal concentration of PGE in the ileum was found by radioimmunoassay to be 3.3 +/- 0.6 ng PGE per g wet wt (chi +/- SE, n = 12). Intramesenteric arterial infusion of acetylcholine (ACh) (100 microgram/min) increased intestinal motility, and PGE concentration rose to 6.7 +/- 0.8 ng/g. Intravenous infusion of indomethacin (4 mg/kg) enhanced spontaneous and ACh-induced motility and abolished the ACh-induced rise in ileal PGE concentration. We conclude that basal PGE synthesis limits the motility of the resting and ACh-stimulated cat ileum.

Acetylcholine↗
PubMed1978

Extrapancreatic glucagon in control of glucose turnover in depancreatized dogs.

Depancreatized dogs have plasma immunoreactive glucagon (IRG), which is of gastric origin and is immunologically indistinguishable from pancreatic glucagon. The effects of extrapancreatic IRG on the tracer-determined rate of glucose production were examined to establish whether this hormone contributes to the hyperglycemia observed in six conscious, depancreatized dogs after insulin withdrawal. The dogs were initially maintained normoglycemic with an intraportal insulin infusion. Insulin withdrawal resulted in a 53 and 70% decrease of serum immunoreactive insulin (IRI) at 60 and 210 min, respectively. At 60 min, plasma glucose rose and Ra increased by 50%. A somatostatin-induced decrease in IRG prevented a further increase in Ra and glucose; after somatostatin withdrawal, IRG, Ra, and plasma glucose increased. Arginine given 1 or 3 h after insulin withdrawal increased IRG by 100 pg/ml, and mean Ra rose by 8.9 mg/kg-min. Thus, in depancreatized dogs with low but detectable serum IRI, IRG suppression is associated with inhibition of Ra and further rise in plasma glucose is prevented. Stimulation of IRG release increases Ra and results in marked hyperglycemia. It is concluded that extrapancreatic glucagon has a diabetogenic effect during acute insulin defiency.

Animals↗
PubMed1978

Prostatic cellular changes after injection of cadmium and lead into rat prostate.

Forty male rats were divided into four groups. Group I served as control. Group II received 1 mg. lead injected into the prostate; Group III received 1 mg. cadmium chloride; and Group IV received 0.5 mg. lead acetate and 0.5 mg. cadmium chloride. Results indicated that lead caused stone formation in the bladder and calcification of both bladder and prostate; cadmium caused reduction in size and weight of prostate, and histological observation showed marked atrophy of the gland, cuboidal epithelium, and squamous metaplasia in the acini of the prostate; there was no synergistic effect of lead acetate and cadmium chloride when combined at the level administered to Group IV.

Animals↗
PubMed1977

Separation and detection of phencyclidine in urine by gas chromatography.

A rapid, sensitive and selective analytical procedure for phencyclidine and one of its metabolites in urine has bee developed. Three techniques have been studied for extraction of the drug from the biological matrix: (a) reversed-phase XAD resin, (b) charcoal absorption, and (c) solvent extraction using chloroform. Temperature-programmed gas chromatography was used to quantitate the illicit drug. Solvent extraction appears to offer the most efficient separation of the drug and its metabolite, as the recovery was 94% and the technique required only 7-8 min per sample. Reversedphase column extraction is also quite useful; although more time-consuming for an indivisual sample, it would be useful for screening purposes.

Anion Exchange Resins↗